[64] Now at that time the group-of-six bhikkhus wore various kinds of thimbles (paṭiggaha) — made of gold, made of silver. People looked down upon, criticized, and spread it about, … "just like householders who enjoy sensual pleasures." They reported this matter to the Blessed One. …
"Bhikkhus, various kinds of thimbles are not to be worn; whoever should wear one commits an offence of wrongdoing (dukkaṭa). Bhikkhus, I allow one made of bone, … made of the spire of a conch shell."
English translation from the Pali (Siam Raṭṭha edition) — under review, not for citation.